Why does a book say DOM event flow has both Capturing and Bubbling? Then won't the event occur twice?

The book Professional Javascript by Zakas says that

1) IE uses event bubbling

2) Netscape us开发者_如何学JAVAes event capturing

3) DOM event flow is first capturing and then bubbling

So, won't the event handler be called twice? What is this DOM event flow, is it the DOM level 2 event handling?

As I understands it, is the following true?

a) IE 6, 7, 8 all uses bubbling

b) FF, Chrome, Safari, Opera all use capturing?

c) jQuery makes everything the same by making it "bubbling"

Maybe this link can shed some light on event propagation